The Use of Chemical Weapons: The Legal Case for Intervention in Syria

By Toby M Cadman

The use of chemical weapons against civilians is a war crime.  In 1993 the Chemical Weapons Convention was signed in Paris.  The purpose of the treaty is to set out a prohibition on developing, producing, purchasing or otherwise acquiring, stockpiling, or retaining chemical weapons, or to transport them directly or indirectly to anyone; never to use chemical weapons or engage in any preparations for doing so; and never to assist, encourage, or induce, in any way, anyone to engage in any activity prohibited by the treaty. 

At present there are 189 State Parties to the Convention. Syria is not one of them, although it is a signatory to the 1925 Geneva Protocol prohibiting the use of poison weapons.  Regrettably the latter provides no basis for the use of force.

It is now beyond doubt, according to the United States, United Kingdom, France, Turkey and the Arab League, that chemical weapons have been used on civilians in Syria, and there appears to be mounting evidence that the Bashar al-Assad regime ordered the use on civilians - at least that's what we're being told.  The Russian position is that reaching such a conclusion is illogical considering that Assad is actually winning the war.  The response to that is twofold. First, Assad was surely testing the resolve of the international community and whether it has the courage to go against Syria's international partners.  Second, the war is dragging on and this provides the Assad regime with finality.

The question now being asked, when so many other questions remain unanswered, is whether this is sufficient to justify legally international military action and what form of action should be taken.  Of course the question must also be asked as to what we are trying to achieve by a short-term military operation in Syria.  The rhetoric is that it is to demonstrate clearly that chemical attacks on civilians will not be tolerated.  The UK at least considers that the chemical weapon attacks by Bashar al-Assad's brutal regime was a calculated step to test the resolve of the international community.  However, is a short-term military campaign likely to prevent further attacks on civilians?  It may well aggravate the situation - this certainly was the case in Libya.  Furthermore, is it really to send a message to Assad or is it more a step in the direction of regime change - however justified that may be.

The clear response to this mounting humanitarian disaster is that a much longer-term strategy is required.  There is of course moral justification for military intervention, but this should be under a UN mandate.  Any resolution considered by the UN Security Council should of course also consider a referral to the International Criminal Court.  Irrespective of whether the attack was carried out by government forces, opposition forces or a third party there is an urgent need for an investigation into the 'situation in Syria'.  There is also a need for setting out a long-term strategy for bringing an end to the conflict and establishing a system of peace and stability on the one hand and rebuilding the Syrian State on the other.  This, regrettably, does not seem to be on the agenda at present and it is solely the short term to 'deter the future use of chemical weapons'. 

Considering the legality of intervention, in respect of Kosovo in the late 1990s, the UK took the position that NATO action was justified on the ground that international law recognises an exceptional right to take military action in a case of overwhelming military necessity.  In October 1998 the Foreign and Commonwealth Office circulated a note to NATO member states declaring that the 'Security Council authorisation to use force for humanitarian purposes is now widely accepted...A UN Security Council Resolution would give a clear legal base for NATO action, as well as being politically desirable.'  However, it went on to argue that that force can also be justified on the grounds of overwhelming humanitarian necessity without a Security Council resolution.

As was determined in Kosovo, there is convincing evidence of an impeding humanitarian catastrophe. Quoting the UK position on Kosovo, as set out in its October 1998 advisory note, 'The UK's view is therefore that, as matters now stand and if action throughout the Security Council is not possible, military intervention by NATO is lawful on the grounds of overwhelming humanitarian necessity.'  The UK Government has adopted the same reasoning for justifying military action in Syria.

The advisory note prepared by the UK Government last week on the legality of military action states

'The use of chemical weapons by the Syrian regime is a serious crime of international concern, as a breach of the customary international law prohibition on use of chemical weapons, and amounts to a war crime and a crime against humanity. However, the legal basis for military action would be humanitarian intervention; the aim is to relieve humanitarian suffering by deterring or disrupting the further use of chemical weapons.' 

The note goes on to state that the UK is seeking a resolution of the United Nations Security Council under Chapter VII of the Charter of the United Nations which would condemn the use of chemical weapons by the Syrian authorities; demand that the Syrian authorities strictly observe their obligations under international law and previous Security Council resolutions, including ceasing all use of chemical weapons; and authorise member states, among other things, to take all necessary measures to protect civilians in Syria from the use of chemical weapons and prevent any future use of Syria's stockpile of chemical weapons; and refer the situation in Syria to the International Criminal Court. 

Going Without a UN Security Council Resolution

The legality of military action, in the event that the UN Security Council is blocked is based, according to the note, under the doctrine of humanitarian intervention provided the following three conditions are met:

(i) there is convincing evidence, generally accepted by the international community as a whole, of extreme humanitarian distress on a large scale, requiring immediate and urgent relief;

(ii) it must be objectively clear that there is no practicable alternative to the use of force if lives are to be saved; and

(iii) the proposed use of force must be necessary and proportionate to the aim of relief of humanitarian need and must be strictly limited in time and scope to this aim (i.e. the minimum necessary to achieve that end and for no other purpose).

The UK Government considers that the three conditions are clearly met.  The legal Guidance states 'The large-scale use of chemical weapons by the regime in a heavily populated area on 21 August 2013 is a war crime and perhaps the most egregious single incident of the conflict.'  It further justifies military action on the basis that all diplomatic attempts to secure a just resolution and end the humanitarian suffering have failed.  There remains a grave risk that further attacks on civilians with the use of chemical weapons.

The Prime Minister, David Cameron, stated last week that the UK National Security Council agreed that 'the world should not stand by' after the 'unacceptable use' of chemical weapons by the Syrian Government. Cameron stated ''We've always said we want the UN Security Council to live up to its responsibilities on Syria. Today they have an opportunity to do that.''  The draft resolution is believed to have advocated for 'all necessary measures' to be taken, but it now appears that military intervention will have to proceed without British involvement following last week's Commons vote unless the Security Council is seized of the matter.

The central issue focuses on the question of legality versus the morality of military intervention.  US Secretary of State, John Kerry, has referred to the moral obscenity of the Bashar al-Assad regime.  He stated that it was 'undeniable' that chemical weapons killed hundreds of civilians and that the government must be held accountable.  US senators in a key committee have now agreed on a draft resolution backing the use of US military force in Syria.

The Russian view is that any military intervention without a UN Security Council resolution would be a violation of international law.  It considers that there is insufficient proof to conclude that the Assad regime is responsible for the attack - if anything the evidence points to the rebels - although it's unclear what evidence they are relying on. The Russian President has stated that he did not rule out supporting a UN Security Council resolution authorising force, if it was proved 'beyond doubt' that the Syrian government used chemical weapons.  However, any military action without a UN mandate would constitute an act of aggression.

This therefore raises the question as to whether there is a sound legal basis for acting without a Security Council resolution.  

Under international law the use of force by one state against another is permissible only under very exceptional circumstances.  The UN Charter prohibits the use of force unless a State (or States) are acting in self-defence or acting pursuant to a Security Council Resolution.  It is quite clear that for States to invoke the self-defence doctrine either individually or collectively to the Syrian conflict would be to redefine the doctrine beyond all recognition.  Therefore, there is not a clear legal basis under self-defence.

There has been much discussion on the applicability of humanitarian intervention, or the Responsibility to Protect (R2P).  As David Kaye, an international legal expert from the UC Irvine School of Law has stated, R2P and the doctrine of humanitarian intervention 'spring from a moral position...But neither exception has the force of law'. Whilst the doctrine clearly demonstrates what is morally correct, it does not properly represent the position of customary international law.  To apply R2P in such circumstances would be to say the Charter is inapplicable. It is debatable that even R2P requires a Security Council resolution.

The issue of the doctrine of humanitarian intervention - distinct from R2P - is less clear.  The position advanced by the UK Government is clearly attractive and sounds right.  However, it still fails to attain the necessary support to have the status customary international law.

Speaking from a moral standpoint military intervention in Syria is clearly warranted.  Twenty-seven months into a bloody conflict it is clear that intervention by the international community has been warranted for some time already.  However, the question should be less of moral obscenity and more legal reasoning - if that is what we are trying to do.

The present position is that the US and France are ready to intervene militarily under the doctrine of humanitarian intervention; a doctrine that the US opposed in relation to Kosovo.  The UK and Germany are not ready to intervene.  There now appears to be growing consensus that the UN inspectors must be given time to complete their investigations and report back to the Security Council.  That will take some weeks yet.  This might be considered as a delaying tactic by some, and the US and France seem to have now bypassed this route by conducting their own analysis, but any intervention in Syria must be legally sound and must be aimed at a more long term solution rather than a short term punitive exercise.

There is a case for intervention in Syria.  Moreover, a short term military campaign aimed at punitive measures will not achieve the desired result.  It will test the resolve of a regime being backed into a corner and it will test the resolve of its international partners.  It will not, in my opinion, bring an end to the conflict.  Far less will it demonstrate that we, collectively, have a long-term strategy for ending the humanitarian crisis in Syria.

Toby Cadman is a Partner at Omnia Strategy LLP, an international law firm based in London and Washington DC, and is an international criminal law specialist.

The views expressed here are the author's own and do not necessarily reflect those of RUSI.